a-a a-b a-c a-t aaa aab aac aae aao aas aat ab- aba abb abc abe abo abs abt ac- aca acb acc ace aco acs act aea aeb aec aee aeo aes aet aoa aob aoc aoe aoo aos aot as- asa asb asc ase aso ass ast at- ata atb atc ate ato ats att baa bab bac bae bao bas bat bba bbb bbc bbe bbo bbs bbt bca bcb bcc bce bco bcs bct be- bea beb bec bee beo bes bet boa bob boc boe boo bos bot bsa bsb bsc bse bso bss bst bta btb btc bte bto bts btt c-- caa cab cac cae cao cas cat cba cbb cbc cbe cbo cbs cbt cca ccb ccc cce cco ccs cct ce- cea ceb cec cee ceo ces cet co- coa cob coc coe coo cos cot csa csb csc cse cso css cst cta ctb ctc cte cto cts ctt eaa eab eac eae eao eas eat eba ebb ebc ebe ebo ebs ebt ec- eca ecb ecc ece eco ecs ect eea eeb eec eee eeo ees eet eo- eoa eob eoc eoe eoo eos eot es- esa esb esc ese eso ess est eta etb etc ete eto ets ett oaa oab oac oae oao oas oat ob- oba obb obc obe obo obs obt oc- oca ocb occ oco ocs oct oea oeb oec oee oeo oes oet oo- ooa oob ooc ooo oos oot os- osa osb osc ose oso oss ost ot- ota otb otc ote oto ots ott saa sab sac sae sao sas sat sba sbb sbc sbe sbo sbs sbt sca scb scc sce sco scs sct se- sea seb sec see seo ses set soa sob soc soe soo sos sot ss- ssa ssb ssc sse sso sss sst sta stb stc ste sto sts stt taa tab tac tae tao tas tat tba tbb tbc tbe tbo tbs tbt tca tcb tcc tce tco tcs tct te- tea teb tec tee teo tes tet to- toa tob toc toe too tos tot tsa tsb tsc tse tso tss tst tta ttb ttc tte tto tts ttt